Prion diseases are a family of fatal neurodegenerative diseases that are caused by infectious misfolded prion proteins (PrPSc) in both animals and humans. Prion diseases can occur spontaneously and can be contracted by multiple routes: consumption of contaminated foods, blood transfusion, organ and tissue transplant, and contamination of medical devices. Prion diseases have a years-, and even decades-long incubation period before onset of symptom. PrPSc are extraordinarily resistant to classic medical decontamination procedures. These factors raise major concerns about potential transmission of the diseases and the need for tools for timely diagnosis. Currently the diseases are diagnosed antemortem imperfectly based on clinical signs of neural disorders, and confirmed only postmortem by neuropathological and immunohistochemical analysis of brain tissue. A sensitive blood screening test is urgently needed for protecting against the risk of disease transmission. This Small Business Innovation Research proposes to apply a novel assay, coupled with sensitive biosensor technology, to develop a living test of prion disease. The assay will be able to quantify normal and variant prions. The initial goal for sensitivity in Phase I is 5 pg/ml in blood with further improvement to be made in Phase II. Prion diseases are infectious,[unreadable] fatal, and have no known cure. Prion disease in cows, commonly known as "mad cow disease", can be transmitted to humans. Highly sensitive tests can prevent infected animals from entering the food chain. Early diagnosis of infected individuals could essentially eliminate the chance of transmitting the disease to others and will also improve the safety of the blood and tissue supplies. Current tests are all postmortem assays using brain tissue. This proposal is to develop a sensitive blood test to detect the disease in its early stage. [unreadable] [unreadable] [unreadable]